Damped fluid displacement support system and method for making the same

ABSTRACT

There is disclosed a substantially completely stable damped liquid displacement support system (11) which comprises an envelope of liquid impervious flexible material having panels (13) and (15) and provided with a valve (17), at least one interior divider (19) provided with a plurality of openings (25) and (27) disposed across the interior of the envelope separating the envelope into at least two compartments (21) and (23), each compartment containing a core (29) of resilient liquid absorbent material and a liquid substantially saturating the core. The opening (25) and (27) permit the liquid to migrate between the compartments (21) and (23) when pressure is applied to the system.

BACKGROUND OF THE INVENTION

This invention relates to support systems. More particularly, theinvention relates to support systems such as mattresses, cushions,upholstery padding and the like which have a liquid in them such as, forexample, waterbeds.

Support systems which contain liquids, such as waterbeds and cushionsand the various benefits thereof are well-known. On the other hand, suchsystems exhibit many disadvantages. For example, conventional waterbedsand cushions produce a kind of wave action or rolling motion when in usedue to the tendency of the water or other liquid inside the system torush rapidly from one part thereof to another when an individual placeshis weight thereon and forces the liquid to flow to another part of thesystem. Moreover, since the envelope containing the liquid in such asystem is typically elastically yieldable, a reaction to the initialliquid surge occurs. This reaction results in a succession ofcountersurges within the envelope until the system reaches equilibrium.The described undamped surging and countersurging of the liquid in suchsystems is not only annoying to most individual users of such systems,but actually results in motion sickness in some of them. In order toobviate the above-mentioned disadvantages, many waterbed manufacturersdo not employ liquid displacement in that portion of the system which isintended to support the head and shoulders of the user. Instead, theyemploy a section of mattressing constructed in the usual mannerutilizing coil springs or other equivalent non-liquid structures.Obviously, this introduces an element of complexity to the manufacturingprocesses and, as well, increased costs.

Some manufacturers of waterbeds have attempted to dampen wave motion invarious ways. For example, in U.S. Pat. No. 3,585,356 solid particles,such as styrofoam are disposed in the liquid for this purpose, whileU.S. Pat. No. 3,600,726 discloses a therapeutic or comfort pad having aflexible film outer envelope filled with a fluid pervious foam material,water or other fluid being introduced thereto through a valve in theenvelope. A flotation pad of somewhat similar construction is disclosedin U.S. Pat. No. 3,611,455. On the other hand, U.S. Pat. No. 3,736,604discloses flap means, as illustrated in FIG. 11 thereof, for thispurpose. In U.S. Pat. No. 4,245,361 there is disclosed a waterbedmattress having a sealed liquid enclosure made of a relatively stiffperipheral cushion of foam material having a central cavity whichcontains a resilient open-cell filling.

A pad having open-cell resilient foam material encased in and bonded toan impervious envelope provided with a valve for communication with theinterior of the envelope to permit passage and containment of fluid isdisclosed in U.S. Pat. No. 3,872,525 to provide a damped liquiddisplacement system. Another liquid displacement system is disclosed inU.S. Pat. No. 3,789,442 which shows a low liquid volume, low weightliquid or water pad for use as a mattress in which a lower cellularfoamed material flexible pad is partially hollowed out for reception ofa flexible material, liquid filled container, an unhollowed portion ofthe pad being provided for a user's head and upper body, which theliquid container does not rest on. An upper flexible pad of the samecellular foamed material extends across the lower pad. The entirestructure described is contained within a flexible water impervioussheath, the structure being inserted through openings in the ends of thesheath which are subsequently closed. Another low-water volume,low-weight water pad for use as a mattress or cushion having awater-filled container sandwiched between upper and lower layers ofcellular foam sheets all surrounded with a water impervious sheet isdisclosed in U.S. Pat. No. 3,702,484.

U.S. Pat. No. 2,748,399, on the other hand, discloses a light-weightfoam rubber cushioning structure in which a bag or chamber having aplurality of compartments, which may either communicate with or beisolated from one another, are filled with air. A layer of foam rubberis supported on the chamber, or the chamber may be sandwiched betweentwo layers of foam rubber. In Swiss Pat. No. 608,951, there is shown acushion structure which has an air-tight and water-tight inner sheathhaving a framework of plastic or elastic material, the sheath beingfilled with a liquid. The inner sheath is subdivided into multipleseparate compartments which may be wholly isolated from each other orwhich may communicate with each other by way of orifaces or valves. Theinner sheath is enclosed in an air-tight or water-tight outer casingwhich has a larger volume than the inner sheath and which also may befilled with a liquid or with air. Finally, U.S. Pat. No. 4,370,768discloses a damped fluid displacement support system having an envelopeof flexible material enclosing a core of resilient liquid-absorbentmaterial which is substantially saturated with a liquid and whichenvelope may also include an interior divider to separate the envelopeinto two compartments.

While various of the above-mentioned references provide systems whichameliorate the wave action or rolling motion of the liquid containedtherein to some extent in comparison to conventional systems, and whilethe last-mentioned reference, U.S. Pat. No. 4,370,768, provides a systemwhich achieves such a result to an even greater extent than the others,there still exists a need for a system to overcome to an even greaterextent the disadvantageous wave action or rolling motion in suchsystems.

Another disadvantage exhibited by conventional liquid displacementsupport systems is that they are relatively unstable in their tendencyto react too rapidly in response to the application or shifting of anyweight or force on them. For example, when an individual lying on such asystem employed as a mattress attempts to roll over, the mattress yieldsrather quickly under him as he presses against it with one of his limbsto initiate movement. The mattress undulates under him as the liquidsurges about within it. Also when the individual attempts to rise fromthe mattress, he has a strong feeling of instability with respect to hissense of balance or equilibrium, since the mattress rapidly gives way ashis weight is shifted to its edge. This instability is also encounteredwhen such liquid displacement support systems are utilized as cushionson a conventional chair, a wheelchair, or on the seat of an automobile.The instability is manifested very clearly in such instances when anindividual attempts to rise from a conventional chair or a wheelchair,or to alight from an automobile. What actually occurs is that the liquidis quickly displaced within the cushion as an individual's weight isshifted and he has the feeling that the cushion is squirting out fromunder him as he attempts to thrust his body upwardly. Furthermore, thenormal rocking motion of a moving automobile or wheelchair is greatlyamplified by conventional liquid filling cushion systems for the samereasons. Once again, while various of the above-mentioned referencesprovide systems which alleviate this disadvantage, that is the relativeinstability in response to the application of force or weight thereto,to some extent and U.S. Pat. No. 4,370,368 achieves such a result to aneven greater extent than various of the other references discussedabove, there still exists the need for a system to overcome thisinstability to an even greater extent.

Another disadvantage associated with conventional liquid displacementsupport systems is the requirement of such systems to be utilized forthe most part in a horizontal disposition. This is so because if arelatively elongated liquid displacement support system or unit isdisposed vertically, or at some considerable angle to the horizontal,the liquid will be drawn by gravity to the lower portions. This causesbulging in these areas while substantially lowering or substantiallycompletely eliminating the cushioning and supporting effects in theupper areas. Consequently, such systems are of only limited usefulnessas backrests or upholstery padding or in hospital beds, for example,where a portion of the bed needs to be tilted at an angle to thehorizontal. U.S. Pat. No. 4,370,678 recognizes this problem and while italleviates it to some extent by providing a system in which a reducedamount of liquid is employed, the movement of which is damped andmodulated by employing a core of flexible cellular material which issubstantially completely saturated by the liquid, there still exists aneed for providing liquid displacement support systems which exhibiteven greater improvement in this respect no matter what their spatialdisposition may be.

A still further disadvantage of conventional liquid displacement supportsystems resides in the fact that most utilize non-compressible, or atmost only slightly compressible liquids, such as water, and they areprovided with flat planar surfaces with which the body of a user comesinto direct contact. Thus, the skeletal protuberances, particularlythose such as the pelvis and hip bones, the coccyx, the spinal vertebra,the shoulder blades, the elbows, the knees and the ankle bones, of thebody of an individual using such systems come into direct contact withthe planar surfaces thereof. Thus, discomfort results to the user due tothe force of the action of such bony protuberances against the planarsurfaces of the systems and the consequent force of the reaction of theliquids in such systems to such force. This disadvantage is particularlytroublesome in situations where such systems are utilized, for example,as cushions or wheelchairs where an incapacitated individual must remainseated thereon for extended periods of time or in hospital beds where anindividual user may have to remain substantially immobile for extendedperiods or have only limited capacity for movement. The same is alsotrue, however, in situations where the systems are employed as cushionsin an automobile and the user must remain in substantially one positionfor extended periods. While various of the above-mentioned referencesalleviate this problem somewhat by the utilization of cushioning means,such as foam padding, there still exists the need for systems whichobviate this problem to an even greater extent.

A still further disadvantage of conventional liquid displacement supportsystems is their weight. Since substantially the entire interior of theliquid cell is filled with liquid, its overall weight is considerable.Again, while various of the above-mentioned references overcome thisproblem to some extent, there still exists a need for systems whichfurther ameliorate this disadvantage to an even greater extent.

From the above discussion it is evident that while liquid displacementsupport systems have evolved to a point where the many disadvantages ofthe earlier systems have been overcome to some extent, such systemsstill exhibit the above-mentioned disadvantages and a need still existsfor the provision of liquid displacement support systems which do notexhibit the same. The present invention fulfills this need.

BRIEF STATEMENT OF THE INVENTION

In accordance with the invention and the broadest aspect thereof, thereis provided a damped liquid displacement support system which comprisesan envelope of flexible material, a core of resilient liquid-absorbentmaterial occupying substantially all of the space within the envelope, aliquid substantially saturating the core, a valve mounted in theenvelope for communication between the interior thereof and its ambiencefor admitting and discharging liquids and gases, and at least oneinterior divider provided with a plurality of openings disposed acrossthe interior of the envelope and separating it into at least twocompartments each containing its own individual liquid-saturated core,and the openings in the interior divider permitting the liquid tomigrate between the compartments of the envelope when pressure or forceis applied thereto.

In another embodiment of the invention the described system includes aplurality of aligned openings disposed in the envelope and the interiordivider with the peripheral edges of the aligned openings joinedtogether at substantially zero height, or inserting tubular meansthrough these openings and sealing the peripheral edges thereof to thetubular means at a distance spaced apart from each other to prevent anyexternal migration of liquid from the envelope while stabilizing theamount of liquid in the envelope. In a further variation of thisembodiment of the invention wherein tubular means are employed, thealigned openings or holes in the interior divider are larger than thoseof the envelope and the peripheral edges of the openings of the envelopeonly are sealed to the tubular means in a spaced relationship, thelarger openings in the interior divider thus providing additionalopenings for liquid to migrate between the compartments.

In accordance with the invention there is also provided a method formaking a damped fluid or liquid displacement support system by placingat least two cores of liquid-absorbent material in an unsealed envelopeof liquid impervious material, the cores substantially filling theenvelope, disposing at least one interior divider provided with aplurality of openings across the interior of the envelope and betweenthe cores and separating the envelope into at least two compartmentseach of which contains its own core and which communicate with eachother through the openings in the interior divider, compressing theenvelope and the cores and forcing substantially all the gasestherefrom, sealing the divider and the envelope to each other aroundtheir peripheral edges, submerging the compressed envelope and cores ina liquid and partially opening the envelope to admit the liquid theretountil the cores are substantially saturated with the liquid and willabsorb no more thereof, and closing the envelope.

In another embodiment of the invention, the described method includesforming a plurality of aligned openings in the envelope and the interiordivider and sealing the edges of the aligned openings together atsubstantially zero height, or inserting tubular means through theseopenings and sealing the peripheral edges thereof to the tubular meansat a distance spaced apart from each other. In a further variation ofthis embodiment of the invention, the method also includes, wheretubular means are employed, forming aligned openings or holes in theinterior divider of greater dimensions than those of the envelope andsealing the peripheral edges of the openings of the envelope only to thetubular means in a spaced relationship and providing additional openingsfor liquid to migrate between the compartments.

THE DRAWINGS

In order to understand the invention more fully reference is directed tothe accompanying drawings which are to be taken in conjunction with thedetailed description of the invention as set forth hereinafter. In thedrawings,

FIG. 1 is a plan view, partially in section, of a damped fluid or liquidsupport system according to the invention illustrating the relationshipof various parts thereof to each other and the disposition of theopenings in the interior divider to permit liquid to migrate between thecompartments thereof;

FIG. 2 is a plan view of another embodiment of a damped liquid supportsystem according to the invention illustrating the utilization of thealigned openings through the envelope and interior divider thereof;

FIG. 3 is a partial cross-sectional view in elevation taken across line2--2 of the system shown in FIG. 2 illustrating the joining of theperipheral edges of an aligned opening through the envelope and theinterior divider at substantially zero height;

FIG. 4 is a partial cross-sectional view in elevation taken across line2--2 of the system shown in FIG. 2 illustrating the utilization oftubular means disposed in an aligned opening through the envelope andthe interior divider and showing the joining of the peripheral edges ofthe aligned opening of the envelope and interior divider to the tubularmeans in a spaced apart relationship;

FIG. 5 is an elevational view in cross-section of a damped liquiddisplacement support system according to the invention illustrating theuse of a relatively thick casing of resilient material surrounding theenvelope;

FIG. 6 is a partial elevational view in cross-section illustrating theconfiguration of a damped liquid displacement system according to theinvention in a compressed and sealed state;

FIG. 7 is a partial elevational view in cross-section of the systemillustrated in FIG. 6 after the core has been substantially saturatedwith a liquid; and

FIG. 8 is an elevational view in cross section taken across line 2--2 ofFIG. 2 of a damped liquid displacement support system according to theinvention, illustrating the use of aligned openings in which theperipheral edges of the aligned openings of the envelope only areattached to the tubular means in a spaced relationship and the alignedopening in the interior divider is larger in size than the openings ofthe envelope and is not attached to the tubular means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1 there is shown a damped liquid displacementsupport system according to the invention comprising a liquid imperviousenvelope or cell 11, including panels or sides 13 and 15. The envelopeis preferably made of a high quality "pool grade vinyl" and has athickness of about 0.020 inch, being free of pinholes and having a coldcrack resistance of at least about minus 20° F. (Ca 30° C.) and whichhas properties that permit the panels or sides from which it isconstructed to be readily fused together by standard dielectric heatingtechniques. A valve 17 is sealed in panel 15 of the envelope, as shownmore particularly in FIG. 5, permitting communication between theinterior of the envelope and its ambience in order to admit anddischarge liquids and gases. The valve is preferably of the positiveclosing type and in this respect it has been found that Type 1020 AFmanufactured by Halkey-Roberts is eminently suitable for this purpose.An interior divider 19, made of the same or similar material as panels13 and 15, is disposed across the interior of the envelope and separatesit into two compartments 21 and 23. The interior divider is providedwith four openings, such as the two arc-shaped openings designated bynumerals 25 and 27, thus permitting communication between thecompartments. While the openings in an interior divider employed in asystem according to the invention are usually located at the cornerswhen the system has a generally rectangular configuration, it is to beunderstood that they may be greater than four in number and arepreferably located along or in the vicinity of the peripheral edges ofthe divider. For example, should the system have a circularconfiguration a plurality of such openings may be located around or inthe vicinity of the circular periphery of the divider. While the shapeof such openings is not critical, the size and location thereof providehighly beneficial effects in a damped liquid displacement support systemaccording to the invention as explained more fully hereinafter.

A core 29 of resilient liquid-absorbent material occupies substantiallyall of the space within the compartments of the envelope. A liquid suchas water or other suitable liquid, substantially saturating the core isalso contained in the compartments of the envelope. The core 29 may bemade of urethane foam or any other suitable resilient, liquid-absorbentmaterial. Material such as urethane having a cellular structure isparticularly useful because it will provide a desirable damping action,as explained more fully hereinafter. The resilient liquid-absorbent cone29 may be adhesively attached with a suitable adhesive, such as thatdescribed below, to the interior divider 19 only, on either one or bothsides thereof, or to one or both panels 13 and 15 of the envelope aswell, the adhesive being applied for this purpose to the panels on thesides thereof which serve as their internal surfaces. It will beappreciated that the panels of the envelope, as well as the interiordivider, which lies across the interior of the envelope in a co-planarrelationship with respect to side panels 13 and 15 thereof, are ofsufficient dimensions to accommodate the core in its liquid-saturated,expanded condition and to permit heat sealing of the panels and dividerto each other along their peripheries as shown at 31.

While the operation of the system generally bears some similarity to theoperation of a conventional waterbed or cushion or other fluiddisplacement support device, it operates in a manner clearly differentfrom such conventional systems and exhibits heretofore unachievedbenefits. The similarity of operation involves the fact that the fluid,in this case water, is forced to migrate from one portion of thecompartments to another as force or weight is applied to the system.However, the similarity with the operation of a conventional waterbed orcushion and other known fluid displacement support devices ends at thispoint and the present system exhibits vital differences due to is uniqueconstruction. For example, in the present device, the water or otherliquid is not permitted to migrate freely from the region where pressureis applied to the compartments of the envelope or cell of the system,yet it is permitted to flow in a modulated, throttled or controlledmanner between the compartments by way of the openings in the interiordivider, such opernings being sized to provide the most desirable flowrate of the water or other fluid between the compartments. Furthermore,the movement of the water or other fluid is, at the same time, modulatedor throttled by the cellular structure of the core which also provides ameasure of firmness to the system due to its resilience. In addition, itwill be appreciated that in the present system the amount of water orother fluid to be displaced is far less than the amount employed in aconventional system.

Consequently, the fluid or liquid displacement support system of thisinvention, as described, exhibits substantially complete stability andno matter what the spatial disposition may be, this stability remainssubstantially unchanged without any evidence of undue bulging at thebottom when it is employed in a relatively vertical plane. Thesubstantially complete stability and absence of undue bulging,heretofore not satifactorily achieved in known liquid displacementsupport systems, is due not only to the fact that the interior of theenvelope or cell 11 is substantially evacuated prior to saturation ofthe core, thus forming a vacuum in the cell if the fluid migratesdownwardly, but primarily to the fact that the fluid is permitted toflow in a modulated, throttled controlled manner out of and into thecompartments, through the openings in the interior divider and, as well,to the fact that the core is prevented from shifing to any appreciableextent, especially where the core material is adhesively attached to theinterior divider and/or the panels of the envelope. Thus, the systemconstantly seeks equilibrium in a slow and controlled manner when aforce or weight is applied thereto and wave action or surging andcountersurging rolling motion is eliminated.

As a practical matter, thereofore, when an individual uses a systemconstructed in accordance with the invention as a bed or a cushion, theadjustment of the system to his weight is slow and gradual, being almostimperceptible. However, since the liquid is permitted to flow andconstantly seeks equilibrium, for a few moments, the individualgradually feels an increasingly comfortable sense of firm support.Should he attempt to maneuver his body, from one position to another, orto stand, he has continuous support from the system because of its slowreaction time to his movements. This imparts a feeling of stability tothe user as compared to the usual feeling of instability associated withconventional systems which make it difficult for individuals such as apatient, for example, to perform basic tasks, such as eating,scratching, dressing and the like and actually produce motion sicknessand even disorientation or hallucination in some individuals. Moreover,he no longer feels that the system is squirting out from under him, whenhe attempts to thrust his body upwardly, as he rises. Furthermore, whenan individual employs a system in accordance with this invention as abed or a cushion, and particularly as the latter, the fluid or liquidtherein, as his body comes into contact with the system, will have agreater tendency to move towards the peripheral edges of the envelope orcell 11 and slowly flow through the openings rather than a relativelypronounced upward flow since the openings in the interior divider areloated along the periphery thereof and permit the liquid to flow betweenthe compartments in a slow, modulated or throttled and controlledmanner.

Still further, it is to be noted that when a person uses the system ofthis invention certain pressure points are normally developedcorresponding to prominent features, particularly the boneyprotuberances, on his body. Now, it is a medical fact that whilepressure reduction through broader weight distribution is achieved bythe present invention, such broader weight distribution is not by itselfthe ultimate solution to overcoming the disadvantages of the developmentof these pressure points. Even when sitting or lying on a flotationsystem capable of reducing pressure dramatically, many individualssuffer discomfort to some degree due to just the normal protrusion ofthe Ischial tuberosities or the coccyx, or the application of even theslightest pressure to areas sensitized by injury or skin trauma.Furthermore, injured or traumatized areas will also heal much morerapidly if there is no applied external pressure to restrict the bloodcirculation. This problem or condition is obviated according to thisinvention in the embodiments thereof illustrated in FIGS. 2 through 4and 8 by constructing an envelope or cell as previously described and,in addition, providing holes or compressed areas under each bone and/orsensitive area in a manner that will support all of the body weight inflotation around the sensitive areas while suspending those areas toeliminate contact with any part of the cell or a base or pad on which itrests, thus preventing any pressure from being applied to them. Byeliminating contact at the areas mentioned, pressure on the remainingbody areas resting on the envelope or cell will increase somewhat.However, due to the capability of the basic envelope or cell todistribute pressure, it will still be well below medically acceptabletolerances. To exercise this conceptual aspect of the invention and atthe same time achieve maximum benefits thereof to an individual user,such as a medical patient or the like, for example, consideration mustbe given to the fact that no two individuals are exactly alike inweight, bone structure and other physical attributes and, as well,specific areas of injury, skin trauma and the like will vary in size andlocation. Therefore, particularly in the area of medical use, it isdesireable for the holes or compressed areas of the envelope or cell tobe located and sized so that pressure on the areas of sensitivity orinjury is eliminated. In accordance with the present invention, this maybe achieved by making a model, form or accurate impression of anindividual's body geography in a block of any of the materials currentlyin use for making impressions in order to accurately locate and size theholes or compressions in the envelope or cell. In such a mold formingprocedure, areas of sensitivity or injury which make no impression inthe mold or impression material may simply be marked with a felt markeror otherwise so that those areas of the envelope or cell may also becompressed as needed to provide flotation of the areas of sensitivity orinjury, that is, to provide compressions or holes to the areas ofsensitivity or injury.

The mold or form so made can then be employed as a pattern or mold fromwhich the base or pad, previously mentioned above, can be made, thusproviding the ultimate in pressure relief for the entire body of asubject or patient. The block or mold can be either hardened orduplicated in a hard material and employed as a base or pad for the cellor envelope. When such a mold or form is used as a base for a dampedliquid displacement support system according to this invention, itprovides the added benefit of aligning an individual, such as a patient,for example, in the proper position in relation to the holes, or inrelation to the seat of a wheelchair or bed in which the system isplaced.

It will be appreciated that for purposes of general use the compressedareas can be located and made to a size so that they will relievepressure at the Ischials and coccyx in order to provide better comfortgenerally for any body structure, such as, for example, the applicationthereof to upholstered furniture, vehicle seats, padded wheelchairs andthe like. It is also to be noted that holes, that is small openings, maybe provided through the envelope or cell which form slight depressions,thereby providing tufting effects in upholstered furniture, as well asacting as means to further secure the system to the furniture structure,particularly when installed in a vertical position as a flotationbackrest. Thus the system is prevented from shifting or becomingdeformed due to vibration or abuse, coupled with normal gravitationaleffects.

It is to be noted further that no matter what particular embodiment asystem of this invention takes in its completed form, specific areas ofthe envelope or cell may be substantially completely compressed. Forexample, where the structure is employed as a mattress, cushion,backrest, or other upholstery item on furniture and certain areasthereof are not required to perform a supporting function, those areasof the structure may be compressed substantially completely to zeroheight and heat sealed in the same manner as the panels of the envelopeand interior divider are joined along their peripheral edges. In otherwords, areas of the structure which do not require flotation may beclosed off substantially completely. A benefit derived from closing offsuch areas is that it provides increased flotation in the balance of theenvelope or cell, thus eliminating the possible need, in certainapplications, to increase the overall height of the envelope or cell andavoiding unnecessary additional weight while maintaining minimal size.

Turning now more particularly to FIGS. 2 through 4 and 8, there is shownin FIG. 2, a system like that of FIG. 1 except that the envelope or cell11 is provided with a plurality of holes or openings 33, 35, 37, 39 and41. It will be appreciated that the openings form compressed ordepressed areas, as shown by area 43 in FIG. 3, in the system and aspreviously described above. As may further be seen from FIG. 3, panels13 and 15 of the envelope and the interior divider 19 may all be heatsealed together at substantially zero height to form a hole or openingwhich is sealed around the peripheral edges thereof to prevent anyexternal flow of fluid or liquid from the system. On the other hand, ina modification of this embodiment, the holes or openings may be providedwith a tubular means 45. As shown more precisely, for example, in FIG.4, hole or opening 35 is provided with tubular means 45 and panels 13and 15 of the envelope as well as interior divider 19, are sealed to thetubular means around the peripheral edges of the openings therein in aspaced relationship with respect to each other, thus creating ashallower or less pronounced compressed or depressed area. Utilizationof the tubular means in a system according to the invention provide asystem which has specific height attributes and which can be adjusted asneeded or desired by employing tubular means of different lengths.

In a still further modification of the embodiment of this invention asillustrated in FIGS. 2 through 4 and 8, there is shown more precisely inFIG. 8 a hole or opening 35 provided with tubular means 45 having panels13 and 15 of the envelope sealed to the tubular means in spacedrelationship around the peripheral edges of the openings therein. Incontrast, however, the hole or opening in the interior divider 19 is oflarger dimensions than those in panels 13 and 15 and is not attached tothe tubular means, thus providing an additonal hole or opening 47 forcommunication between the compartments of the system.

In accordance with this invention the damped liquid displacement supportsystem and the various embodiments thereof as set forth above may be usein the described form as final products. In general, however, it ispreferred that the previously described envelope or cell be disposed inan outer casing of resilient material having the properties of a goodthermal insulator, as shown more particularly in FIG. 5. Referring nowto FIG. 5 such a system is shown there in a configuration which would beuseful as a mattress. A suitable outer casing 49 of resilient materialwhich exhibits good thermal insulating properties surrounds the envelopeor cell 11. Urethane foam is very suitable for this purpose. Althoughnot shown, it will be appreciated that casing 49 may be covered with anysuitable covering material generally used for mattresses so long as itis sufficiently soft and has enough stretchability so as not to restrictthe action of the system described hereinabove. The casing 49 isprovided with a suitable cavity to accept the envelope or cell 11 andmay be fabricated in halves in order to facilitate the assembly of thesystem. In a preferred embodiment of this invention, a suitable glue isemployed to adhere envelope or cell 11 to the inner surface of thecasing 49. The glue should be of a type suitable for bonding a vinyl tofoam such as Scotch-Grip Brand Adhesive Number 1359, manufactured by the3-M Company. The bonding of the envelope or cell 11 to the casing inthis manner serves to keep it in place during its shipment ormanipulation. It also further aids in resisting or reinforces againstthe natural tendency of the envelope or cell to bulge near the bottomwhen it is stood on end, although in this latter respect the cell issubstantially completely stable and free of bulging as described above.

As previously mentioned, a liquid such as water or other suitable liquidor fluid substantially saturates the core in a damped fluid or liquiddisplacement support system in accordance with this invention. Water isthe preferred liquid employed in the practice of the invention. In thisrespect, however, since the inventive system in actual use may besubjected to relatively low temperatures and temperatures even as low assubzero temperatures, it is preferred that the water be employed withadditives which lower its freezing point. A particularly preferredliquid which may be employed in the practice of this invention is,therefore, a liquid comprising 20%, propylene glycol, 4% Natrosol andfurther additives, the remainder being water. Such a mixture is notaffected by great temperature changes and the presence of the propyleneglycol acts as an antifreeze. In addition, propylene glycol and Natrosolprovide a further advantage in that they increase the viscosity of theliquid, such as water, thereby effecting further control over themovement of the liquid and obviate a tendency for a certain amount ofthe liquid to always remain in the most compressed area or areas of thesystem. This further improves the stabilizing, supportive, controllednature of the flotation achieved by the system. Natrosol is a registeredtrademark of Hercules Powder Company, Wilmington, Del., U.S.A. for analkali-soluble cellulose ether.

With respect to fluids or liquids which might be employed in thepractice of this invention it is to be noted that the use of thick gellsof various formulations including petroleums, while they are useful,should generally be avoided for a number of reasons. For example, suchmaterials are relatively heavy and do become firmer with time, losingtheir ability to distribute weight and to reduce pressure. Furthermore,those materials are generally expensive. In contrast, water is readilyavailable and inexpensive even when employed as mixtures with propyleneglycol, Natrosol and other additives.

A damped liquid or fluid displacement support system in accordance withthis invention obviates all of the disadvantages of previously knownconventional systems as mentioned above and in this respect, since manyof the previously known systems require a relatively deep amount ofliquid in order to support body weight particularly without the fluidbeing completeely displaced by the weight, thus causing bottoming out,the overall weight of such systems is considerably greater than a systemin accordance with the present invention since the presence of the corematerial in the instant system considerably decreases the amount ofwater needed in order to substantially completely saturate the core andprovide the necessary weight distributing properties which are achievedby the damped liquid or fluid displacement support system of thisinvention.

While overcoming the various disadvantages of conventional fluiddisplacement support systems, a system in accordance with the instantinvention is also advantageous in that it might be employed in a widevariety of end products. For example, the instant system may bemanufactured in a wide variety of shapes and can be employed as amattress, as a cushion for use in padded wheelchairs or automobiles, oron conventional chairs, and also may be employed as upholstery paddingson furniture items, for example, as flotation backrests on chairs, aswell as flotation armrests. In the area of office furniture,manufacturers are constantly striving to make their chairs moreconforming to the backs of the users and the ways to make the necessaryadjustments to achieve the desired result more facile and workable.Moreover, the time required to make the desired adjustments is alsoconsiderd to be critical. The damped liquid displacement support systemof this invention, however, eliminates these problems since it isautomatically self-adjusting and leveling. It will be appreciated that asystem in accordance with the invention, due to its unique construction,may be suitably shaped for utilization as upholstery padding infurniture items, replacing conventional padding in all respectes whethersuch items are being utilized for business, domestic or medical uses.

It is to be understood that it is within the purview of this inventionto employ different substances for the core, as well as for the liquidmedium, as previously mentioned above, contained therein. Similarly, acasing made of different material may be employed to surround theenvelope or cell. It is to be noted, however, that no matter whatparticular materials are employed to form the casing, or what particularfluids are utilized in the envelope or cell, they should be chosen sothat they will not substantially alter the properties of the finalproduct to the extent that they detract from the required degree offirmness or stability of a system such as described above. For example,in this respect the liquid medium, as well as the material employed forthe core, should not appreciably result in great variations in reactiontime and degree of firmness and stability produced by the invention.

THE METHOD

In accordance with the invention there is provided a method for making adamped fluid displacement support system which comprises in its broadestaspects placing at least two cores of resilient liquid-absorbentmaterial within an unsealed envelope of liquid impervious material, thecores substantially filling the envelope, disposing of at least oneinterior divider provided with a plurality of openings across theinterior of the envelope and between the cores and separating theenvelope into at least two compartments each of which contains its owncore and which communicate with each other through the openings in theinterior divider, compressing the envelope and the cores and forcingsubstantially all the gases therefrom, sealing the divider and theenvelope to each other around their peripheral edges, submerging thecompressed envelope and cores in a liquid and partially opening theenvelope to admit the liquid thereto until the cores are substantiallysaturated therewith and will absorb no more thereof, and closing theenvelope. The sealing step may be carried out either before orsimultaneously with the compressing step. The method preferably alsoincludes surrounding the envelope with a casing and adhesively attachingthe casing, which is preferably made of a resilient foam material havinggood thermal insulating properties, and the envelope to each other.

In addition, the method also includes the forming of a plurality ofaligned openings in the envelope and the interior divider and sealingthe peripheral edges of the openings together. The peripheral edges ofthe aligned openings may be sealed together at substantially zero heightor a tubular means may be inserted through the aligned openings and theperipheral edges of the openings sealed to the tubular means at adistance spaced apart from each other. In those instances where thealigned openings are sealed together at substantially zero height orthey are sealed to a tubular means inserted therethrough in spacedrelationship, the formation and sealing thereof may be accomplishedbefore the compression step or similtaneously therewith.

In accordance with one aspect of the inventive method the alignedopenings in the interior divider are made larger in size than theopenings in the panels of the envelope or cell and only the peripheraledges of the envelope panel openings are to be sealed to a tubular meansinserted through the openings. In accordance with this aspect, thelarger holes are pre-cut in a convenient manner, first, in the cellularcore material which is then adhesively attached to the interior divider,and then cut in the interior divider. After this operation is completed,the holes or openings are then made in the panels of the envelope, thepanels and interior divider with its adhered core material are thenassembled, and the tubular member then inserted through them. Theassembly is then placed in a suitable die, compressed and heat sealed,thus closing the assembly around its peripheral edges and also sealingthe peripheral edges of the openings in the panels of the envelope tothe tubular means while forming an opening in the interior dividerthrough which the tubular means passes. It will be appreciated that inaccordance with this particular aspect of the inventive method theperipheral openings in the interior divider are not sealed to thetubular means. Once again the assembly may be sealed either before orsimultaneously with the compression step.

More specifically, the fabrication of a system in accordance with thisinvention can be carried out by using standard heat sealing die toolingwith certain modification which involves packing the die with a foamrubber or sponge material having a firmness at least twice that of thecore material, so that the core material will be compressed when the dieis actuated and substantially all of the air or other gases containedtherein will be expelled therefrom. In accomplishing the methodgenerally, first, a piece of vinyl is placed on the bed plate of a heatsealing press so that it is centered under the die. This piece willbecome panel 13 of the envelope or cell 11. Next a piece of urethanefoam material 29 is centered on the vinyl, an interial divider 19 laidon top of the urethane foam and centered thereon, another piece ofurethane foam material laid on the interior divider 19 and centeredthereon and finally another piece of vinyl which forms panel 15 of theenvelope is laid on top of the foam and then centered. The top piece ofvinyl has valve 17 fused into it and the valve is in closed position.Subsequently, the heat sealing press is actuated so that the die isbrought down on the assembly. The packing in the die compresses theurethane foam forcing the air or any other gases contained therein to beexpelled. While the die is in the actuated position, radio frequencyheating is applied in the standard way along the peripheral edges of theassembly forming a seal 31. The assembly in a compressed position isshown in FIG. 6 and sealing of the same when in a compressed stateprevents the core 29 from absorbing air when the die is withdrawn. Thus,a flattened envelope or cell 11 is produced consisting of compressedcore 29 in an envelope 11 which is separated into compartments 21 and 23by interior divider 19. It is to be noted that in these cases whereurethane foam is to be adhesively attached to the interior divider only,on either one or both sides thereof, or to both panels of the envelopeas well, the adhesive may be applied to the panels on the side thereofwhich will become the internal surfaces, and to one or both sides of thedivider before these elements are placed on the bed plates of the heatsealing press, or as they are "laid up" on the bed plate.

The compressed envelope or cell is submerged in fluid or liquid,preferably water, the valve 17 opened, and the fluid is permitted toenter the envelope through the valve causing expansion of the core 29 asshown in FIG. 7 until the core will absorb no more. In other words, thecore is substantially saturated. Alternatively, the compressed envelopeor cell may simply be filled with a pressure pump which does not allowany air to enter it. It is to be noted that the vinyl material piecesand the interior divider piece are employed in a size sufficient toaccommodate the expansion of the envelope. This extra material is shownas vertical wall section 51 in FIG. 7.

Once core 29 is saturated, valve 17 is closed and the envelope isremoved from the fluid or liquid, dried, and, optionally, placed withincasing 49 which is made in two halves provided with a suitable cavity toreceive the envelope, preferably being glued to the surfaces of thecavity. As a final step, suitable covering material may be placed aroundthe casing, or the envelope itself in those instances where a casing isnot employed.

It will be appreciated that the peripheral openings in the interiordivider, such as shown at 25 and 27 in FIG. 1, as well as the alignedopenings, such as shown at 33, 35, 37, 39 and 41 in FIG. 2 can bepre-cut as needed in the vinyl material forming the panels of theenvelope and in the interior divider before they are assembled in thedie. Moreover, the aligned openings can be sealed around theirperipheries in the desired manner with respect to height simultaneouslywith the heat sealing of the peripheral edges of the envelope. In suchinstances the die can be suitably modified to accomplish such sealing inaccordance with known techniques. The same is also true when tubularmeans are employed and in such instance the tubular means can beinserted through the aligned openings when assembling the variouselements in the die which will in such cases be modified to accommodatethe presence of the tubular means.

What is claimed is:
 1. A damped liquid displacement support system whichis substantially completely stable with respect to wave action orrolling motion of the liquid contained therein and nonsusceptible to theaccumulation of a substantial amount of said liquid in a particularportion thereof when force is applied thereto, irrespective of thespatial disposition of said system, said support system comprisinganenvelope of flexible liquid impervious material, said envelope havingtwo substantially parallel panels of substantially the same size, eachpanel having a border surface, said border surfaces of said panels beingsealed together in a liquid impervious seam, one of said panels servingas a body supporting surface, a core of resilient liquid-absorbentmaterial occupying substantially all the space within said envelope, aliquid substantially saturating said core, a valve mounted in saidenvelope for communication between the interior thereof and its ambiencefor admitting and discharging liquids and gases, and at least oneinterior divider substantially parallel to and the same size as each ofsaid envelope panels and separating said envelope into at least twocompartments each of which contains its own liquid-saturated core, saidinterior divider having a plurality of peripherally disposed openingsand no other holes therethrough, said openings in the periphery of saidinterior divider being located and sized so as to cause said liquid tomigrate between the compartments of said envelope in a controlledsubstantially uniform flow with substantially no wave action or rollingmotion and without accumulation of a substantial amount of said liquidin a particular portion of said envelope when pressure is applied tosaid envelope having a force component perpendicular to said bodysupporting surface, irrespective of the spatial disposition of saidsystem, whereby an individual may use said envelope as a supportcushion, said liquid within said envelope gradually seeking equilibriumabout that portion of the individual's body contacting said envelope. 2.A damped liquid displacement support system according to claim 1 whereinthe core is a flexible cellular material.
 3. A damped liquiddisplacement support system according to claim 1 wherein the core iscellular polyurethane.
 4. A damped liquid displacement support systemaccording to claim 1 wherein the core of resilient liquid absorbentmaterial is adhesively attached to the interior divider and to theinterior surfaces of the envelope.
 5. A damped liquid displacementsupport system according to claim 1 wherein areas of the envelope aresubstantially completely compressed to reduce or remove pressure atsensitive areas on the body of an individual using the damped liquiddisplacement support system and provide increased floatation in thebalance of the envelope.
 6. A damped liquid displacemet support systemaccording to claim 1 wherein the liquid is a fluid comprising by weight20 percent propylene glycol, 4 percent alkali-soluble cellulose ether,and water.
 7. A damped liquid displacement support system according toclaim 1 including a relatively thick casing of resilient materialsurrounding the envelope.
 8. A damped liquid displacement support systemaccording to claim 7 wherein the casing and the envelope are adhesivelyattached to each other.
 9. A damped liquid displacement support systemwhich responds to changes in applied pressure in a controlled manner andwhich reduces or removes support pressure at sensitive areas of the bodyof an individual using the damped liquid displacement support system,said support system comprisingan envelope of flexible liquid imperviousmaterial, said envelope having two substantially parallel panels ofsubstantially the same size, each panel having a border surface, saidborder surfaces of said panels being sealed together in a liquidimpervious seam, one of said panels serving as a body supportingsurface, a core of resilient liquid-absorbent material occupyingsubstantially all the space within said envelope, a liquid substantiallysaturating said core, a valve mounted in said envelpe for communicationbetween the interior thereof and its ambience for admitting anddischarging liquids and gases, at least one interior dividersubstantially parallel to and the same size as each of said envelopepanels and separating said envelope into at least two compartments eachof which contains its own liquid-saturated core, said interior dividerhaving a plurality of openings disposed along the periphery of saidenvelope, said openings in said interior divider permitting said liquidto migrate in a throttled manner between the compartments of saidenvelope when pressure is applied thereto having a force componentperpendicular to said body supporting surface, and a plurality ofaligned openings disposed in said envelope and said interior divider,said peripheral edges of said envelope and said interior divider formedby said aligned openings being joined together in a liquid imperviousseam around said openings such that areas of compression are formedwithin said envelope, said areas of compression being selectivelypositioned to reduce or remove pressure at sensitive areas on the bodyof an individual using the damped liquid displacement support system.10. A damped liquid displacement support system according to claim 16wherein the aligned openings in the interior divider are of largerdimensions than the aligned openings in the envelope and only thealigned openings of said envelope are joined together around theperipheral edges of said openings.
 11. A damped liquid displacementsupport system according to claim 16 wherein the peripheral edges of theenvelope and the interior divider formed by the aligned openings arejoined together at substantially zero height with respect to each other.12. A damped liquid displacement support system according to claim 16wherein a tubular means is disposed in the aligned openings and theperipheral edges of the envelope and the interior divider formed by saidaligned openings are joined to said tubular means at a distance spacedapart from each other.
 13. A damped liquid displacement support systemaccording to claim 16 wherein the aligned openings in the interiordivider are of larger dimensions than the aligned openings in theenvelope, a tubular means is disposed in the aligned openings, and onlythe aligned openings of said envelope are joined to said tubular meansaround the peripheral edges of said openings at a distance spaced apartfrom each other.
 14. A method for making a damped fluid displacementsupport system comprising the steps of:making a pattern, mold or form ofan individual's body geography, impressing, locating and sizing on saidpattern, mold or form areas of bony protuberances on said body, whilemarking on said pattern, mold or form areas of sensitivity or injurywhich make no impressions thereon, placing on said pattern, mold or format least two cores of resilient liquid absorbent material within anunsealed envelope of liquid impervious material, said coressubstantially filling said envelope, said envelope having twosubstantially parallel panels of substantially the same size, one ofsaid panels serving as a body supporting surface, disposing at least oneinterior divider provided with a plurality of peripherally disposedopenings across the interior of said envelope and between said cores,said interior divider being substantially parallel to and the same sizeas each of said envelope panels, said interior divider separating saidenvelpe into at least two compartments each of which contains its owncore and which communicate with each other through the openings in theperiphery of said interior divider, compressing said envelope and saidcores and forming depressed areas or holes in said envelopescorresponding to the areas of bony protuberances and sensitivity orinjury on said pattern, mold or form while expelling substantially allof the gases thereform, sealing said divider and said envelope to eachother around their peripheral edges and at the depressed areas thereof,submerging the compressed envelope and cores in a liquid and partiallyopening the envelope to emit said liquid thereto until said cores aresubstantially saturated therewith and will absorb no more thereof, andclosing the envelope, thereby forming a damped fluid displacementsupport system having depressed areas or holes conforming to the areasof bony protuberances and sensitivity or injury on said pattern, mold orform which correspond to like areas on said body, said openings in theperiphery of said interior divider being located and sized so as tocause said liquid to migrate between the compartments of said envelopein a controlled substantially uniform flow with substantially no waveaction or rolling motion and without accumulation of a substantialamount of said liquid in a particular portion of said envelope whenpressure is applied to said envelope having a force componentperpendicular to said body supporting surface, irrespective of thespatial disposition of said system, whereby an individual may use saidenvelope as a support cushion, said liquid within said envelopegradually seeking equilibrium about the portion of the individual's bodycontacting said envelope.
 15. A method according to claim 14 wherein thepattern mold or form material is hardened and employed as a base for thedamped fluid displacement support system, the depressions and compressedareas of which system correspond to those of said mold.